Methods and apparatus for detecting a syncMark in a hard disk drive
a hard disk drive and syncmark technology, applied in the direction of recording signal processing, instruments, maintaining head carrier alignment, etc., can solve the problems of reducing data capacity relative to the technique of fig. 1, affecting format efficiency, and affecting the accuracy of syncmark detection
Active Publication Date: 2012-05-29
AVAGO TECH INT SALES PTE LTD
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AI Technical Summary
Benefits of technology
Enables on-the-fly data recovery without reducing data capacity, with enhanced reliability in detecting syncMarks even in the presence of media defects.
Problems solved by technology
The syncMark detector could miss detecting the syncMark, for example, due to signal defects where the read-back signal on the syncMark is destroyed or distorted beyond the tolerance of the syncMark detector.
The second syncMark 240, however, must be inserted into the data and thus impairs the format efficiency, resulting in a reduced data capacity relative to the technique of FIG. 1.
Method used
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[0014]The present invention provides improved techniques for recovering from a failure to detect a syncMark in a hard disk drive. According to one aspect of the invention, a second syncMark is written at the end of a sector, in the place of a postamble 130. FIG. 3 illustrates an exemplary recording format 300 for disk drives that incorporates features of the present invention. As shown in FIG. 3, the disclosed recording format 300 includes a servo address mark (SAM) pattern 110 that identifies the start of the next set of embedded servo information, as well as a first syncMark pattern 120, in a similar manner to FIG. 1.
[0015]In addition, the disclosed recording format 300 includes a second syncMark pattern 330 at the end of a sector, where a postamble pattern 130 would normally be expected in the format of FIG. 1. In this manner, the disclosed recording format 300 allows the second syncMark pattern 330 to be detected, when the first syncMark pattern 120 is missed by the hard disk dr...
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Methods and apparatus are provided for detecting a syncMark in a read channel, such as a hard disk drive. A syncMark is detected in a sector in an iterative read channel by obtaining a sector signal from a storage media, the sector signal comprising a first syncMark, data and a second syncMark substantially at an end of the sector; determining whether the first syncMark is detected in the sector signal; searching for the second syncMark if the first syncMark is not detected in the sector signal; and detecting and decoding the sector signal based on a detection of the second syncMark. The second syncMark may be positioned, for example, following data in the sector signal. The second syncMark can be searched for in a window within the signal sector that is based on an estimated location of the first syncMark.
Description
FIELD OF THE INVENTION[0001]The present invention is related to techniques for syncMark detection techniques in a hard disk drive and, more particularly, to techniques for detecting a second syncMark in a hard disk drive when the first syncMark is not detected.BACKGROUND OF THE INVENTION[0002]Storage systems, such as disk drives, typically include one or more disks or other storage media with a plurality of concentric data tracks. A transducer is typically positioned over a destination track during a write or read operation. Servo head position information is typically recorded on the disk. One common recording format 100 for disk drives, shown in FIG. 1, includes a servo address mark (SAM) pattern 110 that identifies the start of the next set of embedded servo information, as well as a syncMark pattern 120 and a postamble pattern 130 before and after the recorded data 140, respectively.[0003]Typically, a servo demodulator determines where to start searching for a SAM pattern based ...
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IPC IPC(8): G06F13/00
CPCG11B5/596G11B20/10009G11B20/1217G11B20/1403G11B27/3027G11B20/1426G11B2220/20G11B2020/1287G11B2020/1476G11B27/30G11B20/10
Inventor LEE, YUAN XINGSAI, FUMINORIYANG, SHAOHUA
Owner AVAGO TECH INT SALES PTE LTD